Heat exchanger for a thermal coupling

ABSTRACT

A heat exchanger, particularly for a thermal coupling of a glycol/water cooling system circuit and a refrigerant circuit in a motor vehicle includes a plurality of first plates having first flow channels for refrigerant and a first reservoir in fluid communication with the first flow channels integrally formed therein, a plurality of second flow plates having second flow channels for a glycol/water mixture, and a second reservoir mounted to a side of said heat exchanger and in fluid communication with the second flow plates.

BACKGROUND OF INVENTION

[0001] 1. Technical Field of Invention

[0002] The present invention generally relates to a heat exchanger, particularly for thermal coupling of a glycol/water circuit and a refrigerant circuit in motor vehicles.

[0003] 2. Description of the Prior Art

[0004] Heat exchangers are apparatuses, or components, through which heat is indirectly transferred from a first fluid mass flux having a first temperature to a second fluid mass flux having a second temperature, lower than the first temperature. The first and second fluid mass fluxes are separated from one another and pass through the heat exchanger without mixing.

[0005] In a motor vehicle having an internal combustion engine, heat which is generated by the combustion process of the engine is typically disposed to the environment by a cooling system within the vehicle. Under certain operational conditions it is useful to divert a portion of this heat to the interior of the vehicle to heat the passenger compartment. The use of a heat pump makes it possible to use this heat within the passenger compartment. However, because of the low temperature of the diverted heat it is necessary to transfer the heat from the glycol/water circuit of the cooling system to the refrigerant circuit of the heat pump.

[0006] Many generic heat exchangers have been developed for this type of application. Some heat exchangers are particularly designed to handle fluid mass fluxes having high fluid pressures. Other heat exchangers developed for use of different refrigerants in cooling plants/heat pump processes have very small flow cross-sections and filling capacities. In one such heat exchanger, adapted for use with refrigerants at high pressures, the refrigerant passes through the heat exchanger in flat tubes having refrigerant channels of small diameters. Ribs extend between the flat tubes to position the flat tubes at a distance from one another. These flat tubes define an air-refrigerant heat exchanger, used as an evaporator in a cooling plant.

[0007] Such a heat exchanger is not suitable for use with a thermal coupling used to interconnect a glycol/water cooling system circuit and a refrigerant circuit. The size of a heat exchanger of this size prevents the use of a heat exchanger of this type as an additional heat exchanger within a motor vehicle.

[0008] Another type of heat exchanger used flat tubes that are designed to be used with refrigerant at high temperatures, such at a refrigeration circuit using carbon dioxide as the refrigerant. Heat exchangers of this type are not suitable for use with a thermal coupling used to interconnect a glycol/water cooling system circuit to a refrigerant circuit.

[0009] It is therefore an object of this invention to provide a heat exchanger, particularly for exchanging heat between a refrigerant circuit and a glycol/water cooling system circuit, whereby the heat exchanger has a small physical size and works at high rates of transferred heat fluxes, while simultaneously meeting the safety requirement necessary to operate with high pressure refrigerants.

SUMMARY OF THE INVENTION

[0010] The disadvantages of the prior art are overcome by providing a plate heat exchanger having a plurality of first plates with first flow channels for refrigerant and a plurality of second plates with second flow channels for glycol/water mixture. A reservoir for the first plates is integrally formed with the first plates, and a second reservoir for the second plates is mounted to an outer side of the heat exchanger, whereby the second reservoir can be arranged on the same plane with the first reservoir, or offset by 90 degrees from the first reservoir.

[0011] According to another aspect of the present invention, the refrigerant or the glycol/water mixture flows in a plane, whereby the heat between the refrigerant and the glycol/water mixture is transferred in cross and/or parallel flow, countercurrent flow, cross countercurrent flow, or cross concurrent flow. The described heat exchanger has connections for refrigerant inflow, refrigerant outflow, glycol/water mixture inflow, and glycol/water mixture outflow, or is directly connected to another heat exchanger. That is, in particular, the environment of the heat exchanger/cooler of the glycol/water circuit.

[0012] In yet another aspect of the present invention, the heat exchanger is designed such that safety requirements are fulfilled due to small flow cross-sections of the refrigerant channels and a small total filling volume of the heat exchanger.

[0013] In still another aspect of the present invention, the heat exchanger has a relatively small size while providing a large heat-transferring surface.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 is a perspective view of a heat exchanger made from plates;

[0015]FIG. 2 is a top view of a plate having flow channels for refrigerant formed therein;

[0016]FIG. 3 is a top view of a plate with flow channels for a glycol/water mixture;

[0017]FIG. 4 is a top view of a heat exchanger of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0018] The following description of the preferred embodiment of the invention is not intended to limit the scope of the invention to this preferred embodiment, but rather to enable any person skilled in the art to make and use the invention.

[0019] Referring to FIG. 1, a heat exchanger of the present invention is shown generally at 1. The heat exchanger 1 is made of a plurality of first and second plates 2, 4. The first plates include first flow channels 3 which are adapted to allow refrigerant to flow therethrough. The second plates 4 have second flow channels 5 which are adapted to allow a glycol/water mixture to flow therethrough. The flow channels 3, 5 can be designed as either single flow or multi-flow channels.

[0020] The heat exchanger 1 has connections for refrigerant inflow, refrigerant outflow, glycol/water mixture inflow, and glycol/water mixture outflow, or alternatively is directly connected to another heat exchanger 1. Preferably, the heat exchanger uses a refrigerant such as carbon dioxide (R744), tetrafluoroethane (R134a), or propane (R290), however, it is to be understood, that other suitable refrigerants could be utilized without departing from the scope of the present invention.

[0021] Preferably, the first and second plates 2, 4 of the heat exchanger 1 are made of a flat material. The first and second flow channels 3, 5 are created by a mechanical forming process, such as pressing or stamping, milling, etching or laser machining. Preferably, the first and second plates 2, 4 are arranged alternately and form a plate pack.

[0022] The wall thickness of the first and second plates 2, 4 depends upon the particular application, however, preferably, the first and second plates 2, 4 have a wall thickness that is between about 0.2 millimeters and about 5 millimeters. The first and second plates 2, 4 can be attached to one another by soldering, brazing, welding, or other suitable means.

[0023] Referring to FIG. 2, the first plates 2 include first reservoirs 6 for the refrigerant. The flow channels 3 pass through the plate 2 in a preferably meandering manner and connect the first reservoirs 6 within each plate. Preferably, the first reservoirs 6 within the first plates 2 are integrally formed within the first plates 2. Depending upon the application, the refrigerant, and geometrical conditions, the first reservoirs 6 can be shaped either circular, oval, elliptical, rectangular, or as an elongated hole.

[0024] The flow channels 3, 5 in the plates 2, 4 can be circular, semicircular, wedge-shaped, ribbed or not ribbed. Further, the first flow channels 3 of the first plates 2 have a hydraulic diameter of between about 0.1 millimeters and about 4 millimeters. The second flow channels 5 of the second plates 4 have a hydraulic diameter of between about 1 millimeter and about 6 millimeters.

[0025] The hydraulic diameter is defined as the product of the cross-sectional area of the flow channels 3, 5 multiplied by four and then divided by the distance around the periphery of the cross-section of the flow channels 3, 5. Therefore, for a flow channel having a circular cross-section, the hydraulic diameter is equal to the diameter of the circular cross-section.

[0026] Referring to FIG. 3, a second plate 4 having flow channels 5 for the glycol/water mixture includes distance pieces 8, and passage openings 9 for the refrigerant to connect the first reservoirs 6 of two adjacent first plates 2 with one another. Second reservoirs 7 are mounted to either side of the plate pack, in fluid communication with the second flow channels 5 of the second plates 4. The second flow channels 5 extend across the second plates 4 to interconnect the second reservoirs 7. Preferably, the second flow channels 5 are linear and extend across the second flow channels 5 at an angle to the sides of the plate pack.

[0027] Referring to FIG. 4, in an alternate embodiment, the second reservoirs 7 of the second plates 4 includes separators 10. The separators 10 divide the reservoirs 7 into separate chambers. Therefore, the glycol/water mixture passes through only part of the second flow channels 5 in the second plates 4 from one reservoir 7 to the opposite reservoir 7, and from the opposite reservoir 7 through the remaining second flow channels 5 in the same second plate 4, back to the original reservoir 7.

[0028] Depending upon the arrangement of the first and second flow channels 3, 5 and the separators 10 in the heat exchanger 1, any type of flow pattern, such as countercurrent flow, cross flow, parallel flow and concurrent flow can be realized partially or totally.

[0029] The foregoing discussion discloses and describes the preferred embodiments of the invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that changes and modifications can be made to the invention without departing from the scope of the invention as defined in the following claims. The invention has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. 

What is claimed is:
 1. A heat exchanger, particularly for a thermal coupling of a glycol/water cooling system circuit and a refrigerant circuit in a motor vehicle comprising: a plurality of first plates having first flow channels for refrigerant and a first reservoir in fluid communication with said first flow channels integrally formed therein; a plurality of second flow plates having second flow channels for a glycol/water mixture; a second reservoir mounted to a side of said heat exchanger and in fluid communication with said second flow plates.
 2. The heat exchanger of claim 1 wherein said second reservoir is mounted onto said heat exchanger such that said second reservoir is aligned within the same plane as said first reservoirs.
 3. The heat exchanger of claim 1 wherein said second reservoir is mounted onto said heat exchanger such that said second reservoir is offset from said first reservoirs by 90 degrees.
 4. The heat exchanger of claim 1 wherein said first and second flow channels are single flow channels.
 5. The heat exchanger of claim 1 wherein said first and second flow channels are multi-flow channels.
 6. The heat exchanger of claim 1 wherein each of said first flow channels has a hydraulic diameter that is between about 0.1 millimeters and about 4 millimeters.
 7. The heat exchanger of claim 1 wherein each of said second flow channels has a hydraulic diameter that is between about 1 millimeter and about 6 millimeters.
 8. The heat exchanger of claim 1 wherein the shape of said first collectors are one of either circular, oval, elliptical, rectangular, or as an elongated hole.
 9. The heat exchanger of claim 1 wherein each of said first and second plates have a wall thickness that is between about 0.2 millimeters and about 5 millimeters.
 10. The heat exchanger of claim 1 wherein the shape of said first and second flow channels are one of either circular, semicircular, wedge-shaped, ribbed, or non-ribbed.
 11. The heat exchanger of claim 1 wherein said first flow channels and said second flow channels are arranged such that flow of the refrigerant through said heat exchanger is either countercurrent flow, cross flow, or parallel flow relative to flow of the glycol/water mixture.
 12. The heat exchanger of claim 1 wherein said second reservoir includes a plurality of separators to divide the second collectors into different chambers.
 13. A heat exchanger, particularly for a thermal coupling of a glycol/water cooling system circuit and a refrigerant circuit in a motor vehicle comprising: a plurality of first plates having first flow channels for refrigerant and a first reservoir in fluid communication with said first flow channels integrally formed therein, said first flow channels having a hydraulic diameter that is between about 0.1 millimeters and about 4 millimeters; a plurality of second flow plates having second flow channels for a glycol/water mixture, said second flow channels having a hydraulic diameter that is between about 1 millimeter and about 6 millimeters; a second reservoir mounted to a side of said heat exchanger and in fluid communication with said second flow plates and including a plurality of separators to divide the second reservoir into different chambers; each of said first and second plates having a wall thickness that is between about 0.2 millimeters and about 5 millimeters.
 14. The heat exchanger of claim 13 wherein said second reservoir is mounted onto said heat exchanger such that said second reservoir is aligned within the same plane as said first reservoirs.
 15. The heat exchanger of claim 13 wherein said second reservoir is mounted onto said heat exchanger such that said second reservoir is offset from said first reservoirs by 90 degrees.
 16. The heat exchanger of claim 13 wherein said first and second flow channels are single flow channels.
 17. The heat exchanger of claim 13 wherein said first and second flow channels are multi-flow channels.
 18. The heat exchanger of claim 13 wherein the shape of said first collectors are one of either circular, oval, elliptical, rectangular, or as an elongated hole.
 19. The heat exchanger of claim 13 wherein the shape of said first and second flow channels are one of either circular, semicircular, wedge-shaped, ribbed, or non-ribbed.
 20. The heat exchanger of claim 13 wherein said first flow channels and said second flow channels are arranged such that flow of the refrigerant through said heat exchanger is either countercurrent flow, cross flow, or parallel flow relative to flow of the glycol/water mixture. 